I haven't seen any Irish broadsides of DS but even as early as the middle of the 18th century Irish printers were printing all manner of stuff and some of it from the English pleasure gardens. Of course a lot of what was going on in the English theatres was also going on in Dublin.

'new ballad'/ 'new song' on broadsides practically meaningless, a ploy to sell an old ballad with a few words changed. At best it can mean new to this area, or even new on the streets. Which is presumably why the commentator put it in inverted commas.